The Research Center on Cellular Membranes consists of a core facility (protein chemistry laboratory and scanning electron microscope laboratory) and 5 associated research project grants which concern different aspects of membrane biology in normal and diseased cells as indicated below. 1) Under Geometry of membrane proteins, F.M. Richards and collaborators investigate protein distribution in membranes by a variety of penetrant and nonpenetrant labeling reagents, 2) G.E. Palade, M.G. Farquher and collaborators work on functional and biogenetic relationships among cellular membranes involved in the secretory pathways (Membrane interactions in eukaryotic cells), 3) D.S. Papermaster investigates synthesis and assembly of rhodopsin in the discs of the outer segments of retinal rods (Immunocytochemical analysis of membrane biosynthesis), 4) Under Hormone receptors in normal and hypertensive vasculature, J.D. Jamieson and collaborators work on photoaffinity labeling of angiotensin II receptors on vascular smooth muscle, 5) and finally under Membrane proteins and tumorspecific antigens V. Marchesi and collaborators are finishing the work on the primary structure of glycophorin and are beginning to sequence the spectrins.